Martin Mika is an Associated Professor of Chemistry and Technology of Inorganic Materials at the Department of Glass and Ceramics at the University of Chemistry and Technology in Prague.
Prior to this he held an Associated Western Universities/AWU Visiting Scientist Fellowship (awarded 1996) at the Pacific Northwest National Laboratory/PNNL in Hanford/Richland, USA,
and a NATO Research Fellowship (awarded 2007) at the Institute of Applied Physics/IFAC-CNR in Florence, Italy.

Currently, he is the principal investigator of the project “Modulators for free-space optics” funded by the Technology Agency of the Czech Republic. His research interests are in
photonic glass; fast ion-conducting glass; inorganic/organic membranes for fuel cells; high-strength foam glass; x-ray optics for space telescopes; glass for nuclear waste
immobilization; phase equilibria and electrochemistry of glass-forming melts and biomass combustion. He earned his Ph.D. degree in Chemistry and Technology of Inorganic
Materials from the University of Chemistry and Technology in Prague. His research group consist of 2 assistants, 11 students and a technician. In 1986 he was awarded the
first price at the International Student Conference in Prague; in 2003 he was awarded the Vittorio Gottardi Award from the International Commission on Glass (ICG); in 2013
he was awarded the Preciosa Award for his pedagogical achievements and in 2014 he was awarded the Czech Glass Society Award. He is a member of the Czech Glass Society and
the ICG Technical Committee TC10 “Optical Properties of Glass and Coated Products”.

Fast infrared modulators, with a response time to an electric signal of less than 1 µs, are required for high speed processing of optical signals in free space communications.
For these modulators, new materials with a high electro-optic coefficient are needed. Because the electro-optic coefficient of heavy metal glasses doped with metal nanoparticles
can reach very high values, these materials are promising for such application. In this work, we developed a new glass based on a PbO-Bi2O3-Ga2O3 system, which was doped with
Ag+ ions for nanoparticle precipitation and with Sb2O3 as a reducing agent. The glass was melted at 1000 °C for 35 min and then cast into a steel mould. Using Sb2O3, Ag+ ions
were successfully reduced to metallic silver Ag0, and during heat treatment nanoparticles of a defined size were formed by the clustering of mobile Ag0 atoms. The electro-optic
coefficient of the glass was measured in an optical system comprising a laser source, a polariser, a glass sample, a quarter wave plate, an analyser, a diaphragm and a detector.
The laser light source was operated in a continuous regime at a wavelength of 2090 nm. The maximum of the transmittance peak was influenced by the high voltage (5–27 kV) applied
on the glass sample. From the rotation angle of the analyser, the electro-optical coefficient b was calculated. The highest value of b (5.9·10-11 m·V-2) was measured for the glass
containing nanoparticles with the optimized mean size of 7 nm that were precipitated by heat treatment at 350 °C for 35 min. Another advantage of this glass was that in the range
of 550–2750 nm it had a transmittance of above 70%, which is high enough to achieve low optical signal attenuation in the near infrared region. Collectively, our results indicate
that the developed glass with Ag0nanoparticles of the optimized size could be applied to the construction of fast infrared modulators with a response time of less than 1 µs to an
electric signal.